1. Technical Field
The present invention relates to heat dissipation units and more particularly to a heat dissipation unit for use in heat dissipation.
2. Description of Related Art
The trend toward thin and lightweight electronic apparatuses leads to downsized components of the existing electronic apparatuses at the cost of generating heat. The heat thus generated becomes the major obstacle in improving the performance of electronic apparatuses and systems. In a preliminary attempt to enhance heat dissipation of components inside electronic apparatuses, the industrial sector put forth heat pipes and vapor chambers which are efficient in heat transfer.
A vapor chamber is a rectangular case (or panel). Capillaries are disposed on the inner wall of a casing of the vapor chamber. The space defined by the inner wall of the casing and disposed within the casing is filled with a working fluid. A heat-generating component, such as a CPU, a southbridge and northbridge, a transistor, or a MCU, is attached to one side (i.e., evaporation region) of the casing and adapted to absorb the heat generated from the heat-generating component such that the working fluid, which is in a liquid state, evaporates at the evaporation region of the casing and thus turns gaseous to thereby transfer heat to a condensation region of the casing. The gaseous working fluid is cooled down at the condensation region to condense and turn liquid. Then, the liquid working fluid returns to the evaporation region by gravity or capillarity to continue with the gas-liquid cycle, thereby dissipating heat at uniform temperature efficiently.
Heat pipes share the same principle and theory with vapor chambers. Essential structural features of a heat pipe are as follows: a hollow-cored portion of the heat pipe with an annular cross section and a caliber defined by the annular cross section is filled with metal powder (or occupied by braided reticulated capillaries); ringlike capillaries are formed on the inner wall of the heat pipe by sintering; afterward, the heat pipe has a vacuum created inside and is filled with a working fluid; finally, the heat pipe gets closed to thereby form the required heat pipe structure. The working fluid is heated up at an evaporation portion of the heat pipe so as to evaporate and spread to a condensation end of the heat pipe. The working fluid is gaseous at the evaporation portion; in its course of leaving the evaporation portion and then spreading to the condensation end, the gaseous working fluid is gradually cooled down and eventually turned liquid by condensation, before flowing back to the evaporation portion through the capillaries.
The only difference between a vapor chamber and a heat pipe lies in the way of conducting heat. The former carries out heat conduction in a two-dimensional planar manner, whereas the latter carries out heat conduction in a one-dimensional linear manner.
Accordingly, it is imperative to use the aforesaid two heat transfer units more efficiently.